Online monitoring of flu in Belgium.

Please cite this paper as: Devroey et al. (2011) Online monitoring of flu in Belgium. Influenza and Other Respiratory Viruses 5(5), 351–356. Background  The diagnosis and treatment of patients with the A(H1N1) pandemic flu caused some serious burden for general practitioners (GPs) in the summer and autumn of 2009. Objective  The aim of this study was to track the incidence of influenza and influenza-like illness (ILI) in Belgium and to describe the characteristics of the affected patients. Methods  In July 2009, the Belgian online influenza surveillance system (BOISS) was set up to monitor the spread of influenza and ILI. Registrations were made by 93 GPs from all 10 Belgian provinces who participated at least 1 week during the first 12 months of the registration. Only patients who met the WHO criteria for flu were recorded. Results  In total, 1254 patients (53% men) with influenza or ILI were included. Mainly younger persons were affected: 43% was under the age of 20 years. A risk factor for influenza-related complications was determined in 19% of cases, mainly patients with chronic respiratory problems. A treatment with oseltamivir or zanamivir was prescribed in 13%, and 3% of the patients was admitted to a hospital. The time of the peak incidence (44th week) and the magnitude (623 cases per week per 100 000 inhabitants) corresponded with the figures of the existing paper-based registration network. The small sample size and possible reporting biases may have influenced the findings of the study. Conclusions  The BOISS provides a good alternative to conduct surveillance activities for influenza and ILI in Belgium. It provides complementary information regarding ILI compared to the existing data capturing.